NEWPORT, Maine — Traffic will be disrupted in the coming weeks as crews from the Maine Department of Transportation begin the preliminary work of replacing the Main Street Bridge that crosses the Sebasticook River’s east branch in downtown Newport.

Traffic over the bridge will be reduced to one lane of alternating, one-way traffic regulated by flaggers, according to a press release from the MDOT. The first phase of the project, which is expected to last up to three weeks, involves the shoulders and slopes at either side of Main Street, which is also U.S. Route 2. This preliminary work is in advance of a full road and bridge closure that is scheduled to begin May 1 and continue though Labor Day.

When the bridge is closed in May, smaller vehicles will be detoured through North Street and Elm Street. Truck traffic will be diverted to Routes 7, 222 and 143. All detour routes will be marked with signage. The project also involves paving projects on North and Elm streets as well as upgrades to the North Street Bridge.

CMP Constructors of Freeport is the contractor for the $1.7 million bridge replacement. The Main Street Bridge was originally constructed in 1930.